Filter element for a liquid filter

ABSTRACT

An annular filter element, including: a filter medium having circumferentially closed about an axis and extended along the axis, the axis defining an axial direction; wherein the filter medium has a radially outer flow face and a radially inner flow face, the radially inner flow face surrounding an inner clean space in the filter element; wherein the filter element is through-flowable radially from a radial outside to a radial inside of the filter element; a water separation screen inserted into the clean space, the water separation screen formed separately from the filter element, the water separation screen connected to the filter element or to a component situated at the filter element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 15/016,572,filed, Feb. 5, 2016, which is a continuation of internationalapplication No. PCT/EP2014/066711, filed Aug. 4, 2014 and designatingthe United States, the international application claiming a prioritydate of Aug. 5, 2013, based on prior filed German patent application No.10 2013 012 918.4, the entire contents of the aforesaid US application,aforesaid international application and the aforesaid German patentapplication being incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a filter element for a liquid filter,in particular for fuel.

BACKGROUND OF THE INVENTION

The publication WO 2004/082804 A1 describes a filter system for dieselfuels, which has an annular particle filter as a filter element in afilter housing. Also, an annular coalescing element is connectedupstream of the filter element, which has the object to aggregatedroplets of water dispersively present in the fuel into larger dropletsto facilitate the water separation. The coalescing element is mountedupstream of the filter element; both components are mounted about acenter pipe centrally situated in the receiving space of the filterhousing, which serves to discharge the cleaned fuel.

When filtering fuel, first the coalescing element is through-flownradially from the outside to the inside, a separation of droplets ofwater occurring at the interior wall of the embracing filter housing,which outflow downward into a water reservoir. Subsequently, the fuel ispassed radially from the outside to the inside through the filterelement and the cleaned fuel is axially discharged via the center pipe.

Furthermore, it is known from the publication EP 1 326 693 B1 tothrough-flow an annular filter element radially from the outside to theinside, having a cylindrical clean space having a center pipe, forfiltering hydraulic oil. The filter device has a bypass valve betweenthe raw side and the clean side, which is loaded with force in theclosing position by a pressure spring, which is braced at a screenhousing protruding into the interior of the filter element. When openingthe bypass valve, the unfiltered fluid flows through the wall of thescreen housing into the clean space.

SUMMARY OF THE INVENTION

The object of the present invention is to effectively separatedispersively contained droplets of water with simple, constructivemeasures when filtering liquids.

The filter element according to the present invention is inserted into aliquid filter, which advantageously is a fuel filter, preferably adiesel fuel filter. An application for, for example, filtering hydraulicoil is, however, also possible.

In a filter housing, the liquid filter has an annular filter element,which particularly serves as a particle filter and which is radiallythrough-flown from the outside to the inside. The interior of the hollowcylindrical filter element forms the clean space via which the cleanedfluid is axially discharged. A center pipe may be inserted into theclean space, adding stability to the filter medium of the filter elementwhich, for example, is embodied in a pleated manner.

The filter element has a water separation screen which is inserted intothe interior of the filter element, if applicable, into the center pipe.The water separation screen forms a component configured separately fromthe filter element or from the center pipe and is connected to thefilter element or a component situated at the filter element. Thedroplets of water, which are included in the liquid, thus, for example,in the fuel or the hydraulic oil, are separated at the water separationscreen. The clean space in the filter element is axially flow-connectedat one end to a water collecting space situated in the filter housingand, at the other end, to a liquid outflow line, via which the cleanedfluid is discharged from the liquid filter. The discharge of theseparated water at the water separation screen on the one hand and ofthe cleaned liquid on the other, thus, occurs in axially oppositedirections from the clean space within the filter element. This, forexample, enables an arrangement of the liquid filter in which the watercollecting space is situated in the bottom area of the filter housingand the cleaned fluid is discharged axially upwards from the cleanspace. The water received into the water collecting space may, forexample, be discharged from the filter housing via a valve. Thus, theoutflow of separated droplets of water from the water separation screeninto the water collecting space is carried out in the direction of theweight of the droplets of water.

The water separation screen may be inserted in the center pipe and isthrough-flown by the cleaned fluid. Advantageously, the outer diameterof the water separation screen is smaller than the interior diameter ofthe center pipe. The cleaned fluid flows radially from the outsidethrough the openings in the wall of the water separation screen to theinside and subsequently flows axially from the clean space. The dropletsof water carried along in the liquid are separated at the outer shell ofthe water separation screen, which, following the weight force, areguided downwards at the outer wall of the water separation screen in thedirection of the water collecting space.

The connection between the water separation screen and the filterelement or a component of the filter element is particularly carried outin a releasable manner, for example, via a latch connection so that whenthe latch position is achieved, the water separation screen ispositively and/or non-positively connected to the filter element or to acomponent of the filter element. Expediently, the water separationscreen is connected to an end plate which is fitted at the end face ontothe filter medium of the filter element. It is categorically alsopossible to connect the water separation screen to the center pipe.

Preferably, the water separation screen is cylindrically formed, aconical embodiment of the water separation screen being alsoconceivable. The water separation screen expediently extends over thetotal axial length of the clean space or of the center pipe in the cleanspace.

According to a further expedient embodiment, a coalescing elementexpediently integrated in the filter element is, in addition to thefilter element, situated in the liquid filter. The fluid to be cleanedis a dispersive mixture of two liquids, for example, fuel havingdispersively embedded water, which are to be separated from each other.With the aid of the coalescing element, fine droplets of water may bejoined to larger droplets, however, without causing a separation. Thus,only larger droplets of water are generated in the coalescing elementwhich, after through-flowing the coalescing element, are separated atthe water separation screen located in the clean space. The coalescingelement is, for example, situated on the clean side of the filterelement, particularly between the radial interior side of the filtermedium of the filter element and the center pipe. It may be alsoconsidered that the coalescing element is situated on the raw side ofthe filter element or that it is integrated into the filter element.

For a flow-proof connection between the raw side and the clean side ofthe filter element, it is advantageous to provide a sealing elementbetween the water separation screen and the component of the filterelement at which the water separation screen is held. Insofar as thewater separation screen is connected to the end plate, the sealingelement may be situated between a collar of the water separation screenand the end plate. The collar is integrally formed with the waterseparation screen and is located at the end face of the water separationscreen. It may be expedient to configure the collar having a greaterouter diameter than the separation shell of the water separation screen.

The sealing element between the water separation screen and thecomponent of the filter element is either integrally formed with thecollar, particularly as a sealing lip molded onto the collar, or formedas a separate sealing element in the form of a sealing ring.

A further exemplary embodiment relates to an annular filter element fora liquid filter, through-flowable radially from the outside to theinside, having an interior clean space in the filter element into whicha water separation screen is inserted, which is formed separately fromthe filter element and which is connected to the filter element or acomponent situated at the filter element, the filter element beingformed by a coalescing element. Thus, first the coalescing element andsubsequently the water separation screen is through-flown, both forminga joint assembly. A particle filter is not mandatory in this exemplaryembodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and expedient embodiments may be concluded from thefurther claims, the description of the figures and the drawings.

FIG. 1 shows a perspective view of a liquid filter for filtering fuel;

FIG. 2 shows a longitudinal section through the liquid filter havingmarked flow arrows to indicate the flow path;

FIG. 3 shows a perspective, partially sectional view of a filterelement, which is part of the liquid filter, having a water separationscreen situated in the interior clean space;

FIG. 4 shows a further, partially sectional illustration of the filterelement;

FIG. 5 shows an enlarged view of detail V from FIG. 4;

FIG. 6 shows an end face connection between the water separation screenand an end plate of the filter element in a variation of the embodiment.

In the figures, same components are provided with the same referencecharacters.

DESCRIPTION OF THE INVENTION

FIG. 1 perspectively shows a fluid filter 1 for filtering fuel,preferably diesel fuel. In a filter housing 2, liquid filter 1 has afilter element for filtering the fuel. In the upper end face region offilter housing 2, a heating device 3 is located, in which the suppliedfuel is preheated before it is fed into the filter element in filterhousing 2. A radial inflow line 4 for supplying the unfiltered fuel anda radial outflow line 5 for discharging the filtered fuel is alsolocated in the upper region of filter housing 2.

FIG. 2 shows liquid filter 1 in a longitudinal section. Filter housing 2accommodates annular filter element 6, which is through-flown radiallyfrom the outside to the inside by the fluid to be filtered. Accordingly,the cylindrical interior in filter element 6 forms clean space 7 fromwhich the cleaned fluid is axially discharged.

A center or support pipe 8, which preferably is made out of plastic andbraces the filter medium of filter element 6 and which providesstability to said filter medium, is inserted into clean space 7 offilter element 6. Central pipe 8 lines clean space 7.

A coalescing element 9 delimited radially inwards by center pipe 8 islocated on the radially interior side of the filter medium of filterelement 6. An agglomeration of finely distributed droplets of water inthe fuel occurs in coalescing element 9 so that said droplets accumulateinto larger droplets.

A water collecting space 10, in which water separated when filtering thefluid is collected, is located in the bottom region near the ground infilter housing 2. The collected water can be discharged from watercollecting space 10 in the filter housing via a bottom sided opening anda valve.

A water separation screen 11, embodied as a hollow cylinder and havingan outer diameter which is smaller than the interior diameter of centerpipe 8, is inserted into clean space 7 so that an intermediate annularspace is formed. Water separation screen 11 extends axially like centerpipe 8 over the total length of clean space 7 or of filter element 6.The droplets of water carried along in the fuel, are separated at theouter surface shell of water separation screen 11. As indicated by thevertical downward pointing arrow, the separated droplets of water aredischarged via the bottom axial end face of clean space 7 into watercollecting space 10.

The wall of water separation screen 11 has a plurality of passageopenings, via which the cleaned fuel may through-flow radially inwardsfrom the annular space between center pipe 8 and water separation screen11 into the interior of water separation screen 11. Subsequently, thecleaned fuel liberated from the water droplets is axially discharged viathe end face of clean space 7 lying axially on the top, which isflow-connected to outflow line 5.

FIG. 3 shows filter element 6 in a perspective and partially sectionalview. Filter medium 12 of filter element 6 is embodied as a pleatedfilter and is enclosed on both end faces by respectively one end plate13, 14. In the area of upper end plate 6, via the central opening ofwhich the cleaned fluid is discharged from clean space 7, waterseparation screen 11 has a radially widened collar 15 connected in alatch-closing manner via snap or latch hooks 16 to end plate 13. Latchhooks 16 are molded at the inward facing side at end plate 13 orintegrally formed with end plate 13 (see also FIGS. 4, 5). In theconnected state, latch hooks 16 engage behind a circumferential,radially outer ring shoulder at collar 15.

As may particularly be concluded from FIG. 5, a sealing lip 17, whichabuts at the radially inner side of latch hooks 16, is molded adjacentto the free end face and, in the radially outer area, to collar 15.Latch hooks 16 may optionally also be configured as a continuouscircumferential latch ring at the bottom side of end plate 13. Aflow-proof seal between the radially outer clean side having watercontaining fuel and the radially inner clean side having fuel notcontaining water is provided via sealing lip 17.

End plate 13 has on its axially outward facing end face an axiallyprotruding support collar 20, onto which a cover 18 is fitted. On theradially inner side of support collar 20, a sealing ring 19 is located,which, as may be concluded from FIG. 3, is braced radially outwards at asection of end plate 13.

As may further be concluded from FIG. 5, the free end face of collar 15is, in the assembled state, located directly below end plate 13. Duringassembly, water separation screen 11 has to be inserted axially from theopposite side into clean space 7 or center pipe 8.

FIG. 6 shows a variation of the embodiment of filter element 6, in whichthe sealing between water separation screen 11 and upper end plate 13,in contrast to the preceding exemplary embodiment, is not carried outvia a molded sealing lip but via a separately configured sealing ring21. Sealing ring 21 is braced radially inwards at a circumferential ringshoulder at end face support collar 20 of water separation screen 11.Sealing ring 21 abuts radially outwards at the inner surface of latchhooks 16 or, in the case of a circumferential embodiment, of the latchcollar, which is integrally formed with end plate 13 and which islocated at the bottom side of end plate 13. For installation, waterseparation screen 11 may be inserted in the axial direction from abovethrough upper end plate 13 into the clean space in filter element 6.

What is claimed is:
 1. An annular filter element, comprising: a filtermedium having circumferentially closed about an axis and extended alongthe axis, the axis defining an axial direction; wherein the filtermedium has a radially outer flow face and a radially inner flow face,the radially inner flow face surrounding an inner clean space in thefilter element; wherein the filter element is through-flowable radiallyfrom a radial outside to a radial inside of the filter element; an endplate having: an axial inner surface; and an opposite axial outersurface; wherein the axial inner surface of the end disk is arranged onan axial end face of the filter medium; and a water separation screeninserted into the clean space, the water separation screen formedseparately from the filter element, the water separation screenconnected to the filter element or to a component situated at the filterelement.
 2. The filter element according to claim 1, wherein the filterelement has an end plate arranged on an axial end face of the filtermedium; wherein the water separation screen is connectable to the endplate.
 3. The filter element according to claim 2, wherein the waterseparation screen has a collar arranged proximate to an axial end of thewater separation screen; wherein a sealing element is provided betweenthe collar and the end plate.
 4. The filter element according to claim3, wherein the sealing element is configured as a sealing lip integrallymolded onto the collar.
 5. The filter element according to claim 3,wherein the sealing element is configured as a separate sealing ringsituated between the collar and the end plate.
 6. The filter elementaccording to claim 3, wherein the water separation screen has aseparation shell having an outer diameter; wherein the collar has anouter diameter that is greater than the outer diameter of the separationshell.
 7. The filter element according to claim 2, wherein the waterseparation screen is connected via a latch connection to the end plate.8. The filter element according to claim 1, wherein the water separationscreen is cylindrically formed.
 9. The filter element according to claim1, wherein the water separation screen is conically formed.
 10. Thefilter element according to claim 1, wherein a coalescing element isarranged adjacent to the filter element.
 11. The filter elementaccording to claim 10, wherein the coalescing element is arranged at aclean side of the filter element.
 12. The filter element according toclaim 1, comprising: a tubular center pipe is inserted into the cleanspace of the filter element; the water separation screen is insertedinto and arranged in the center pipe.
 13. A liquid fuel filter,comprising: a filter housing; a filter element according to claim 1arranged within an interior of the filter housing.
 14. The liquid fuelfilter according to claim 13, wherein the housing includes a watercollecting space for collecting water separated from the fuel; whereinthe clean space in the filter element is flow-connected at a first axialend to the water collecting space; wherein the clean space isflow-connected at an opposing second axial end to a liquid outflow linefor the cleaned liquid.